U.S. patent application number 12/267746 was filed with the patent office on 2009-03-05 for method for producing nitrogen to use in under balanced drilling, secondary recovery production operations and pipeline maintenance.
Invention is credited to Mark Dunbar, William James Hughes.
Application Number | 20090060801 12/267746 |
Document ID | / |
Family ID | 34861826 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090060801 |
Kind Code |
A1 |
Hughes; William James ; et
al. |
March 5, 2009 |
METHOD FOR PRODUCING NITROGEN TO USE IN UNDER BALANCED DRILLING,
SECONDARY RECOVERY PRODUCTION OPERATIONS AND PIPELINE
MAINTENANCE
Abstract
The invention uses a feed of atmospheric air and mixes the air
with hydrogen. The hydrogen and air mixture is fed into a catalytic
reactor where a deoxygenation reaction occurs. The deoxygenation
reaction uses a platinum catalyst to produce water from oxygen and
hydrogen. The nitrogen passes through the catalytic reactor without
reacting with the hydrogen, the oxygen, or the water. The water is
separated from the nitrogen in a dryer. The nitrogen may then be
used in drilling and production operations. The water is fed into
an electrolyzer where an electrolysis reaction occurs. The
electrolyzer passes an electrical current through the water to
produce gaseous oxygen and hydrogen. The hydrogen is recycled back
to the catalytic reactor and the oxygen may be vented or sold.
Inventors: |
Hughes; William James;
(Bixby, OK) ; Dunbar; Mark; (Tulsa, OK) |
Correspondence
Address: |
DUKE W. YEE
YEE & ASSOCIATES, P.C., P.O. BOX 802333
DALLAS
TX
75380
US
|
Family ID: |
34861826 |
Appl. No.: |
12/267746 |
Filed: |
November 10, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10786756 |
Feb 25, 2004 |
7468173 |
|
|
12267746 |
|
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Current U.S.
Class: |
422/169 ;
166/63 |
Current CPC
Class: |
C01B 21/0422 20130101;
C01B 5/00 20130101; C01B 13/02 20130101; E21B 43/168 20130101 |
Class at
Publication: |
422/169 ;
166/63 |
International
Class: |
B01D 53/86 20060101
B01D053/86; E21B 43/00 20060101 E21B043/00 |
Claims
1.-23. (canceled)
24. An apparatus for separating air into nitrogen and oxygen, the
apparatus comprising: a mixing chamber that mixes air and a
reducing gas to obtain an inlet gas; wherein the air comprises
oxygen and nitrogen; wherein the inlet gas is fed into a reactor;
wherein the reactor reacts the reducing gas with the oxygen in the
air to substantially eliminate the oxygen, thereby producing an
effluent gas comprising nitrogen and water; a first separator that
separates the nitrogen in the effluent gas from the water in the
effluent gas; and a second separator that separates the water in
the effluent gas into a hydrogen gas and an oxygen gas.
25. The apparatus of claim 24 further comprising: wherein the
nitrogen is used in a well site operation.
26. The apparatus of claim 24 further comprising: wherein the
oxygen gas is sold; and wherein the hydrogen gas is recycled into
the inlet gas.
27. The apparatus of claim 26 wherein the second separator uses
electrolysis to separate the hydrogen gas and the oxygen gas from
the water.
28. The apparatus of claim 26 further comprising: wherein the
oxygen gas is sold or vented.
29. The apparatus of claim 28 wherein the second separator uses
electrolysis to separate the hydrogen gas and the oxygen gas from
the water.
30. The apparatus of claim 24 wherein the reaction occurring in the
reactor between the reducing gas and the oxygen in the air is a
catalyzed reaction.
31. The apparatus of claim 30 wherein the catalyst is platinum.
32. The apparatus of claim 24 wherein the reaction occurring in the
reactor between the reducing gas and the oxygen is a deoxygenation
reaction.
33. The apparatus of claim 24 wherein the reactor maintains a
temperature high enough to support the reaction and low enough to
prevent damage to the catalyst.
34. The apparatus of claim 25 wherein the reactor maintains a
temperature between approximately 200.degree. F. and approximately
1000.degree. F.
35. The apparatus of claim 24 wherein the reducing gas is
hydrogen.
36. The apparatus of claim 24 wherein the reducing gas is a gaseous
hydrocarbon.
37. The apparatus of claim 24 wherein the well site operation is
drilling.
38. The apparatus of claim 24 wherein the well site operation is
under balanced drilling.
39. The apparatus of claim 24 wherein the well site operation is
production.
40. The apparatus of claim 24 wherein the well site operation is
secondary recovery.
41. The apparatus of claim 24 wherein the well site operation is
pipeline cleaning.
42. The apparatus of claim 24 further comprising: a heat exchanger
used to regulate the temperature of the reactor.
43. The apparatus of claim 42 wherein the heat exchanger is an air
cooler.
44. The apparatus of claim 24 wherein the first separator is a
dryer.
45. The apparatus of claim 44 wherein the dryer is a heat
exchanger.
46. The apparatus of claim 44 wherein the dryer is a chemical
dryer.
47. The apparatus of claim 24 wherein the heat from the reaction
between the reducing gas and the oxygen is used to produce
electricity.
48. An apparatus for use at a well site, the apparatus comprising:
means for mixing air and a reducing gas to obtain an inlet gas;
wherein the air comprises oxygen and nitrogen; means for feeding
the inlet gas into a reactor; means for reacting the reducing gas
with the oxygen in the air to substantially eliminate the oxygen,
thereby producing an effluent gas comprising nitrogen and water;
means for separating the nitrogen in the effluent gas from the
water in the effluent gas; and means for using the nitrogen in a
well site operation.
49. The apparatus of claim 48 further comprising: means for
separating the water in the effluent gas into a hydrogen gas and an
oxygen gas; means for selling the oxygen gas; and means for
recycling the hydrogen gas into the inlet gas.
50. The apparatus of claim 49 wherein the means for separating the
hydrogen gas and the oxygen gas uses electrolysis.
51. The apparatus of claim 48 further comprising: means for
separating the water into a hydrogen gas and an oxygen gas; and
means for selling or venting the oxygen gas.
52. The apparatus of claim 51 wherein the means for separating the
hydrogen gas and the oxygen gas from the water uses
electrolysis.
53. The apparatus of claim 48 wherein the reaction between the
reducing gas and the oxygen is a catalyzed reaction.
54. The apparatus of claim 53 wherein the catalyst is platinum.
55. The apparatus of claim 48 wherein the reaction between the
reducing gas and the oxygen is a deoxygenation reaction.
56. The apparatus of claim 48 wherein the means for reacting
maintains a temperature high enough to support the reaction and low
enough to prevent damage to the catalyst.
57. The apparatus of claim 56 wherein the means for reacting
maintains a temperature between approximately 200.degree. F. and
approximately 1000.degree. F.
58. The apparatus of claim 48 wherein the reducing gas is
hydrogen.
59. The apparatus of claim 48 wherein the reducing gas is a gaseous
hydrocarbon.
60. The apparatus of claim 48 wherein the well site operation is
drilling.
61. The apparatus of claim 48 wherein the well site operation is
under balanced drilling.
62. The apparatus of claim 48 wherein the well site operation is
production.
63. The apparatus of claim 48 wherein the well site operation is
secondary recovery.
64. The apparatus of claim 48 wherein the well site operation is
pipeline cleaning.
65. The apparatus of claim 48 wherein a heat exchanger is used to
regulate the temperature of the means for reacting.
66. The apparatus of claim 65 wherein the heat exchanger is an air
cooler.
67. The apparatus of claim 48 wherein the nitrogen in the effluent
gas is separated from the water in the effluent gas using a means
for drying.
68. The apparatus of claim 67 wherein the means for drying is a
heat exchanger.
69. The apparatus of claim 67 wherein the means for drying is a
chemical dryer.
70. The apparatus of claim 48 wherein the heat from the reaction
between the reducing gas and the oxygen is used to produce
electricity.
71. An apparatus for use at a well site, the apparatus comprising:
means for mixing air and a reducing gas to obtain an inlet gas;
wherein the air comprises oxygen and nitrogen; means for feeding
the inlet gas into a reactor; means for reacting the reducing gas
with the oxygen in the air to substantially eliminate the oxygen,
thereby producing an effluent gas comprising nitrogen and water;
wherein a heat exchanger is used to regulate the temperature of the
means for reacting; means for separating the nitrogen in the
effluent gas from the water in the effluent gas; means for using
the nitrogen in a well site operation; means for separating the
water in the effluent gas into a hydrogen gas and an oxygen gas
using electrolysis; means for selling the oxygen gas; means for
recycling the hydrogen gas into the inlet gas; wherein the reaction
between the reducing gas and the oxygen is a deoxygenation reaction
using platinum as a catalyst; wherein the means for reacting
maintains a temperature high enough to support the reaction and low
enough to prevent damage to the catalyst; wherein the means for
reacting maintains a temperature between approximately 200.degree.
F. and approximately 1000.degree. F.; wherein the heat from the
reaction between the reducing gas and the oxygen is used to produce
electricity.
72. The apparatus of claim 71 wherein the reducing gas is
hydrogen.
73. The apparatus of claim 71 wherein the reducing gas is a gaseous
hydrocarbon.
74. The apparatus of claim 71 wherein the well site operation is
drilling.
75. The apparatus of claim 71 wherein the well site operation is
under balanced drilling.
76. The apparatus of claim 71 wherein the well site operation is
production.
77. The apparatus of claim 71 wherein the well site operation is
secondary recovery.
78. The apparatus of claim 71 wherein the well site operation is
pipeline cleaning.
79. The apparatus of claim 71 wherein the heat exchanger is an air
cooler.
80. The apparatus of claim 71 wherein the means for drying is a
heat exchanger.
81. The apparatus of claim 71 wherein the means for drying is a
chemical dryer.
Description
FIELD OF THE INVENTION
[0001] The present invention is a method for separating air into
gaseous oxygen and gaseous nitrogen, and using the nitrogen to
induce under balanced drilling conditions, to improve the
production of oil in secondary recovery operations, or to clean a
pipeline. In all applications, the oxygen that is produced is
considered a by-product that can be sold or vented.
BACKGROUND OF THE INVENTION
[0002] Traditional drilling operations employ the circulation of a
weighted drilling fluid (i.e. mud) such that the hydrostatic
pressure of the drilling fluid contained in a well bore is equal to
or greater than the pressure exerted by the formation being
drilled. Traditional drilling can be preferable because the weight
of the mud column prevents flammable hydrocarbons from entering the
well bore. However, traditional drilling also creates operational
challenges due to a positive pressure differential between the well
bore and the formation. Examples of operational challenges include
differential sticking of the drill pipe, reservoir damage due to
filter cake, increased costs of well completion, and reduced
permeability and production from the formation.
[0003] In response to these challenges, a drilling method called
under balanced drilling has been developed. In under balanced
drilling, the hydrostatic pressure of the drilling fluid is less
than the pore pressure of the formation. Under balanced drilling
has the potential to be hazardous because oil and gas could blowout
from the well bore, releasing a large amount of flammable
hydrocarbons into the atmosphere. However, improvements in blowout
prevention equipment have made it possible to drill safely in an
under balanced condition. Benefits of under balanced drilling
include increasing the drilling rate, limiting lost circulation,
limiting reservoir damage, reducing differential sticking, and
reducing the cost of well completions. Under balanced drilling can
be beneficial when drilling directional and horizontal wells that
target oil and gas reservoirs for production purposes.
[0004] To accomplish under balanced drilling conditions, the weight
of the drilling fluid must be reduced so that the hydrostatic
pressure within the well bore is less than that of the formation.
Standard methods of reducing weight of the drilling fluid include
replacing the drilling fluid with a gas (i.e. air, nitrogen or
natural gas drilling), infusing the drilling fluid with a gas to
reduce the density of the mud (i.e. gas-cut mud drilling), and
creating a foam from a gas and a liquid and using the foam as the
drilling fluid (i.e. foam drilling). In each case, under balanced
drilling involves the introduction of a gas into the well bore. The
gases that are used for drilling may also be used during
post-drilling operations for various well-completion and production
activities such as cleaning out well bores, cleaning pipelines, and
reservoir injection to stimulate production in secondary recovery
projects. Secondary recovery is an oilfield term used to describe
any process such as the injection of gas into a reservoir to
restore oil production from a subsurface formation where the
primary drive mechanism and reservoir pressure have been depleted.
Pipeline cleaning, also known as pigging, is the process of forcing
a device called a pig that is made of hard rubber, plastic or metal
and shaped like a sphere or a cylinder through a pipeline to remove
condensate that collects in low places in the pipeline.
[0005] For both under balanced drilling and other gas-related
oilfield applications, the traditional options for gas selection
include air (79% N.sub.2 and 21% O.sub.2), carbon dioxide
(CO.sub.2), natural gas, and nitrogen (N.sub.2). The oxygen in the
air presents the risk of down hole fire or explosion because the
oxygen can promote an explosive atmosphere when mixed with
hydrocarbons within the well bore. The resulting well bore fire can
be very costly and disruptive to drilling operations. Use of air or
carbon dioxide also presents the risk of increased corrosion of
down hole pipe and equipment, requiring expensive corrosion
prohibition and treatment to the drilling or production equipment.
The use of natural gas can be prohibitively expensive for sustained
drilling operations and increases the risk of hazardous exposure
for drilling personnel.
[0006] Of the available gas options, nitrogen provides the most
benefit for under balanced drilling while presenting the fewest
associated risks. Nitrogen is inert and does not create a risk of
down hole fires or explosions. Nitrogen is not corrosive and does
not require additional corrosion protection for the drilling or
production equipment. Nitrogen is also considered relatively safe
to use, as it is not flammable and does not present an undue safety
risk for personnel involved in the drilling operation. Therefore,
it is highly desirable to have a supply of pure nitrogen available
for use during under balanced drilling, secondary recovery projects
and other oilfield operations and such as pipeline pigging. If the
nitrogen is generated at the well site, producing field or pipeline
site, the generation of nitrogen should be cost effective in that
it does not place an undue financial burden on the under balanced
drilling project, the secondary recovery operation, or pipeline
cleaning process.
[0007] The nitrogen producing equipment must meet other demands
that are unique to drilling, production, and pipeline operations.
The physical location of the drilling operation, secondary recovery
project, or pipeline access point can be remote, so the nitrogen
production equipment must be able to be transported to remote
places. Drilling operations typically last less than three months,
so the nitrogen producing equipment must be mobile enough to move
from one location to another along with the drilling equipment. The
nitrogen producing equipment must also be priced such that the cost
of the nitrogen producing equipment does not prohibit the use of
nitrogen at the well site. Thus, a need exists for a relatively
inexpensive method for producing nitrogen in which the nitrogen
producing equipment can be frequently moved to remote
locations.
[0008] There are four generally understood methods for generating
nitrogen. The first generally understood method for generating
nitrogen is cryogenic distillation. Cryogenic distillation is a
process in which air is condensed into a liquid form, and then
separated into component streams in a distillation column.
Cryogenic distillation can produce extremely pure streams of
nitrogen and oxygen. Unfortunately, the cryogenic distillation
process is very expensive and is generally considered cost
prohibitive for drilling uses.
[0009] The second generally understood method for generating
nitrogen is pressure swing adsorption (PSA). PSA is a process in
which air is confined in a chamber with an adsorption catalyst and
drastic and/or rapid changes in the pressure of the gas causes one
type of molecule, oxygen, to adsorb onto the catalyst, while the
other molecule, nitrogen, exits the catalyst chamber. The catalyst
type and residence time can be varied to achieve desired purity
levels of the resultant nitrogen stream. However, the PSA process
is not preferable because the PSA equipment can be too large and
heavy to be easily moved from one location to another. The cost of
frequently compressing the air can be prohibitive as well.
[0010] The third generally understood method for generating
nitrogen is membrane filtration. Membrane filtration is a process
in which air passes through a membrane unit which separates some of
the oxygen from the nitrogen by means of membrane pores sized to
filter the larger molecule, oxygen, out of the smaller molecule,
nitrogen. While the membrane quality can be varied to achieve
different purity levels of nitrogen, even with the most efficient
membranes sufficient oxygen remains in the nitrogen to create
corrosion. Thus, the membrane filtration method does not generate
nitrogen of sufficient purity to eliminate the need for corrosion
inhibitors for under balanced drilling conditions.
[0011] The fourth generally understood method for generating
nitrogen is combustion. Combustion reactions provide for the
burning of a substance in the presence of air to consume the oxygen
in the air while leaving the nitrogen intact. One drawback of
combustion is that the nitrogen product is mixed with carbon
dioxide as a result of the reaction. The combustion reaction can
also produce other impurities such as carbon monoxide (CO) and
nitrogen oxide (NO.sub.X). These pollutants are undesirable in the
nitrogen and must be removed in order for the nitrogen stream to be
usable for under balanced drilling operations. Therefore,
combustion is not an appropriate means for nitrogen production at
the well site.
[0012] The prior art has previously addressed the need for nitrogen
at the well site. For example, U.S. Pat. No. 6,494,262 (the '262
patent) entitled "Non-Cryogenic Production of Nitrogen for On-Site
Injection in Well Clean Out" discloses a method for cleaning out a
well using a compressed inert gas, such as nitrogen, produced by
the non-cryogenic separation of air. The inert gas is delivered to
the region of the well where undesirable matter has collected. In
particular, the '262 patent provides for the inert gas to be
supplied onsite by the separation of air using a membrane
filtration or a PSA system. Neither membrane filtration nor PSA can
provide the purity level of nitrogen required to eliminate
corrosion during under balanced drilling operations. Therefore, a
need exists for an improved method for producing nitrogen at a well
site that is able to produce nitrogen of sufficient purity to
significantly reduce the potential for corrosion in under balanced
drilling operations, secondary recovery projects, and pipeline
maintenance.
[0013] U.S. Pat. No. 6,206,113 (the '113 patent) entitled
"Non-Cryogenic Nitrogen for On-Site Downhole Drilling and Post
Drilling Operations Apparatus" discloses a method for enhancing
hydrocarbon production by delivering a nitrogen rich gas produced
from a non-cryogenic source into the well or reservoir where the
hydrocarbons are located. In particular, the '113 patent provides
for the inert gas, such as nitrogen, to be supplied onsite by
separating air using membrane filtration or PSA. Neither membrane
filtration nor PSA provides the purity level of nitrogen required
to prevent corrosion during under balanced drilling, post drilling
operations commonly known as secondary recovery and pipeline
maintenance. Therefore, a need exists for an improved method for
producing nitrogen at a well or field site that is able to produce
nitrogen of sufficient purity to be used in under balanced
drilling, secondary recovery, and pipeline maintenance
operations.
[0014] The four generally understood methods for producing nitrogen
are not preferable for under balanced drilling operations. The cost
of the cryogenic distillation equipment is prohibitive for under
balanced drilling operations. The membrane filtration units
typically do not create nitrogen of sufficient purity to prevent
corrosion in under balanced drilling operations. The PSA units are
bulky and are not sufficiently portable for under balanced drilling
operations. The combustion equipment is inexpensive and portable,
but produces nitrogen that contains undesirable contaminants
rendering the nitrogen unsuitable for under balanced drilling
operations. Therefore, a need exists for a method of producing
sufficiently pure nitrogen using mobile equipment, in which the
nitrogen is suitable for under balanced drilling, secondary
recovery, and pipeline maintenance operations.
[0015] Recently, a new method of removing oxygen from air, the
deoxygenation reaction, has been developed. The deoxygenation
reaction uses a platinum catalyst to react the oxygen in air with a
hydrogen feed to produce water. The products of the deoxygenation
reaction are water and nitrogen. When the correct ratios of air and
hydrogen are used, virtually all of the oxygen in the air is
converted into water. The resulting nitrogen/water stream can be
cooled to condense the water out of the nitrogen, if desired. This
process is illustrated in U.S. Pat. No. 6,274,102 (the '102 patent)
entitled "Compact Deoxo System." The deoxygenation reaction in the
'102 patent is useful and could be used for under balanced drilling
operations. However, because oxygen is a very valuable gas, it
would be more desirable for the overall process to separate the
oxygen from the nitrogen instead of consuming the oxygen. The
oxygen could then be sold to help finance the cost of the
deoxygenation equipment, drilling equipment, drilling operations,
and production operations. Therefore, a need still exists for a
method for separating air into oxygen and nitrogen in which the
oxygen stream is not consumed in the process.
[0016] Consequently, a need exists for a process to produce
nitrogen in which the process equipment can be easily moved to
remote locations. The need extends to a nitrogen production method
that is able to produce nitrogen of sufficient purity for under
balanced drilling, secondary recovery operation, or pipeline
maintenance. A need exists for a method of producing nitrogen that
is relatively contaminant-free. Finally, a need exists for
producing nitrogen in which the oxygen is not consumed in the
nitrogen generation process.
SUMMARY OF THE INVENTION
[0017] The present invention provides a method for the generation
of nitrogen onsite for use in drilling, production, and other
oilfield operations. This method employs a deoxygenation reaction
to derive nitrogen (N.sub.2) from a catalyzed reaction of air and
hydrogen (H.sub.2). The applications for use of the nitrogen
include, but are not limited to, under balanced drilling,
post-drilling operations, well completion, secondary recovery
production operations, and pipeline maintenance. The preferred
embodiment provides for all components of the process to be
contained on skids that can be hauled to a drilling or field
location. The skids can be loaded onto a trailer and moved from one
location to another. The preferred embodiment further provides for
one primary product and one by-product. The primary product of
nitrogen is used during the under balanced drilling process,
secondary recovery production operations, and pipeline cleaning
process. The by-product of oxygen is available for commercial use
or sale. The preferred embodiment provides for the sale of the
oxygen by-product for medical or other distribution in such a way
as to make the process more economically feasible for use in under
balanced drilling, secondary recovery operations, or pipeline
cleaning process by offsetting the cost of the project as a
whole.
[0018] The invention feeds water into an electrolyzer where an
electrolysis reaction occurs. The electrolyzer passes an electrical
current through the water to separate the two elements that form
water: oxygen and hydrogen. The oxygen may be vented or sold. The
hydrogen is combined with atmospheric air and fed into the
catalytic reactor where a deoxygenation reaction occurs. The
deoxygenation reaction uses a platinum catalyst to produce water
from oxygen and hydrogen. The nitrogen passes through the catalytic
reactor without reacting with the hydrogen, the oxygen, or the
water. The water is separated from the nitrogen in a dryer and is
recycled back to the electrolyzer. The nitrogen may then be used in
under balanced drilling, secondary recovery production operations,
or pipeline cleaning process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The novel features believed characteristic of the invention
are set forth in the appended claims. The invention itself,
however, as well as a preferred mode of use, further objectives and
advantages thereof, will best be understood by reference to the
following detailed description of an illustrative embodiment when
read in conjunction with the accompanying drawings, wherein:
[0020] FIG. 1 is an illustration of a process flow diagram of the
present invention;
[0021] FIG. 2 is an illustration of a physical diagram of the
present invention;
[0022] FIG. 3 is an illustration of a well site utilizing the
present invention;
[0023] FIG. 4 is an illustration of secondary reservoir recovery
using the present invention; and
[0024] FIG. 5 is an illustration of the pipeline cleaning apparatus
using the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] The present invention is a method for separating air into
oxygen and nitrogen and using the nitrogen gas for under balanced
drilling operations. FIG. 1 illustrates the flow of materials
through the present invention. The present invention consumes an
inlet feed of air and separates the air into two effluent streams:
an oxygen stream and a nitrogen stream. The equipment depicted in
FIG. 1, along with the pumps, valves, and controls associated with
the equipment, can be mounted on at least one structural steel skid
for easy movement from one well site to another. When mounted on a
skid, the present invention does not require any additional support
structure other than electricity, which is readily available at the
well site. The present invention does not require any support
structure because the inlet air can be consumed from the
atmosphere, the effluent nitrogen is stored within a storage tank
until needed for the under balanced drilling operations, and the
effluent oxygen can be vented to the atmosphere. In the preferred
embodiment, the effluent oxygen can be bottled and sold to help
finance the cost of capital expenditures and drilling
operations.
[0026] As seen in FIG. 1, air (79% N.sub.2, 21% O.sub.2) enters the
invention from the atmosphere. The air is fed into compressor 102
that pressurizes the air to a suitable pressure to enter mixing
chamber 104. Mixing chamber 104 mixes a stoichiometric or other
preferable ratio of hydrogen (H.sub.2) from storage tank 122 and
air from compressor 102. The mixture of hydrogen and air is fed
into catalytic reactor 106.
[0027] Catalytic reactor 106 is a plug-flow type reactor that
allows the deoxygenation reaction to occur. The deoxygenation
reaction consumes the hydrogen (H.sub.2) and the oxygen (O.sub.2)
in the inlet feed to produce water (H.sub.2O). The nitrogen
(N.sub.2) passes through the catalytic reactor without reacting
with the hydrogen, the oxygen, or the water. The reaction is
described as:
2H.sub.2(g)+O.sub.2(g).fwdarw.2H.sub.2O(g)+heat
[0028] The heat of reaction is -1854 kJ/mol of water formed. Thus,
for every one percent of oxygen in the volume of gas passing
through the catalyst, there is an estimated 300 degree Fahrenheit
(.degree. F.) rise in temperature across the catalyst. In the
preferred embodiment, the catalyst is platinum. Platinum, however,
has a temperature limit of 1300.degree. F. under which it is an
effective catalyst for the deoxygenation reaction. Due to the
platinum limitations and the exothermic properties of the
deoxygenation reaction, a heat exchanger is needed to keep the
catalyst sufficiently cooled.
[0029] A temperature control system is also needed to be installed
in the equipment to maintain the catalytic reactor's 106
temperature in a range that is hot enough for the initiation of the
reaction and cool enough to protect the catalyst. The temperature
control system connects to the catalytic reactor 106 as well as to
heat exchanger 108, to regulate the temperature of the catalyst
through a feedback loop. The catalytic reactor 106 will initially
be heated by resistance heaters to a temperature hot enough for the
reaction to begin (approximately 200.degree. F.). Once the reaction
begins, the generated heat of reaction will be sufficient to
maintain the continued deoxygenation reaction. To prolong the
platinum catalyst's life, the temperature control system will use
heat exchanger 108 to maintain the catalytic reactor's 106
temperature within an appropriate temperature range (approximately
200-1000.degree. F.). The preferred embodiment also provides for
safety controls to be installed that will shut down the reaction
process if the safety limits are exceeded.
[0030] Heat exchanger 108 cycles a cooling fluid through catalytic
reactor 106. The cooling fluid is then fed back into heat exchanger
108 where the cooling fluid passes through a series of tubes. A fan
underneath the tubes cools the tubes and, therefore, the fluid
inside the tubes. Alternative to heat exchanger 108, persons of
ordinary skill in the art will appreciate that the present
invention can be configured with other types of heat exchangers
such as a shell and tube type heat exchanger, a plate fin heat
exchanger, or a bayonet type heat exchanger. Persons of ordinary
skill in the art are aware of other types of heat exchangers other
than those described herein.
[0031] In an alternative embodiment, the present invention may also
be configured with an electrical generator, such as a steam
turbine, that is connected to the heat exchanger. In this
embodiment, the heat from the exothermic reaction in catalytic
reactor 106 can be used to generate electricity. The electricity
may be used to run electrolyzer 118, any other equipment of the
present invention, or the drilling operations at the well site.
[0032] The effluent from catalytic reactor 106 is a stream of water
and nitrogen. The water and nitrogen stream passes into dryer 110.
Dryer 110 condenses the water out of the nitrogen and water stream.
Dryer 110 is preferably connected to heat exchanger 111. However,
in alternative embodiments, dryer 110 may also be a chemical dryer
or a condenser. Persons of ordinary skill in the art are aware of
other types of dryers 110.
[0033] Heat exchanger 111 cycles a cooling fluid through dryer 110.
The cooling fluid is then fed back into heat exchanger 111 where
the cooling fluid passes through a series of tubes. A fan
underneath the tubes cools the tubes and, therefore, the fluid
inside the tubes. Alternative to heat exchanger 111, persons of
ordinary skill in the art will appreciate that the present
invention can be configured with other types of heat exchangers
such as a shell and tube type heat exchanger, a plate fin heat
exchanger, or a bayonet type heat exchanger. Persons of ordinary
skill in the art are aware of other types of heat exchangers other
than those described herein.
[0034] The nitrogen gas from dryer 110 is stored in storage tank
112. When needed for under balanced drilling operations, the
nitrogen is compressed in compressor 114 and sent down the well
bore to the under balanced drilling equipment. Persons of ordinary
skill in the art are aware of various types of under balanced
drilling equipment that require nitrogen. The nitrogen may also be
used for any other type of drilling and/or production operations.
Persons of ordinary skill in the art are aware of other needs for
nitrogen gas at the well site including cleaning out the well bore
and enhancing the production of hydrocarbons such as oil and
gas.
[0035] The water effluent from dryer 110 is stored in storage tank
116. Depending on the efficiency and throughput rate of catalytic
reactor 106 and electrolyzer 118, storage tank 116 may need to be
periodically recharged with water. Persons of ordinary skill in the
art will appreciate that storage tank 116 may need to be
periodically recharged with water for other reasons including
start-up the present invention. The water then passes to
electrolyzer 118. Electrolyzer 118 passes an electrical current
through water in a process called electrolysis. The electrical
current breaks the water molecule bonds and produces gaseous
hydrogen at the cathode and gaseous oxygen at the anode. The
reaction can be described as:
2H.sub.2O(g)+electricity.fwdarw.2H.sub.2(g)+O.sub.2(g)
The oxygen is collected at the anode and is stored in storage tank
120. The oxygen may then be bottled and packaged for sale to the
public. Alternatively, the oxygen from electrolyzer 118 may be
vented to the atmosphere. Electrolyzer 118 may be powered by
electricity or by a solar panel. In an alternative embodiment,
electrolyzer 118 is powered by electricity generated from the heat
generated by the exothermic reaction of catalytic reactor 106.
[0036] The hydrogen from electrolyzer 118 is captured at the
cathode and stored in storage tank 122. Depending on the efficiency
and throughput rate of catalytic reactor 106 and electrolyzer 118,
storage tank 122 may need to be periodically recharged with
hydrogen. Persons of ordinary skill in the art will appreciate that
storage tank 122 may need to be periodically recharged with
hydrogen for other reasons including start-up the present
invention. The hydrogen in storage tank 122 is then recycled into
mixing chamber 104. A compressor (not shown) may be implemented
between storage tank 122 and mixing chamber 104 to pressurize the
hydrogen prior to entering mixing chamber 104.
[0037] The equipment of the present invention may be sized
according to the desired flow of nitrogen or oxygen out of the
present invention. In an embodiment producing 4.88 lb/min (79
mol/min) of nitrogen gas, the process flow streams are depicted in
table 1 below:
TABLE-US-00001 TABLE 1 Total Flow N.sub.2 O.sub.2 H.sub.2 H.sub.20
(mol/ (mol/ (mol/ (mol/ (mol/ Stream Phase min) min) min) min) min)
A Gas 100 79 21 0 0 B Gas 142 79 21 42 0 C Gas 121 79 0 0 42 D Gas
79 79 0 0 0 E Liquid 42 0 0 0 42 F Gas 21 0 21 0 0 G Gas 42 0 0 42
0
The stream identification letters A through G correspond to the
circled letters in FIG. 1.
[0038] The present invention uses hydrogen as reducing gas in the
deoxygenation reaction of the present invention. While hydrogen is
the preferred reducing gas, persons of ordinary skill in the art
are aware of other reducing gases that are usable in the present
invention. For example, gaseous hydrocarbons such as methane,
ethane, propane, and butane may be used in the present invention.
Persons of ordinary skill in the art are aware of other reducing
gasses that may be used in the present invention.
[0039] FIG. 2 depicts the present invention on a skid 100.
Placement of the equipment of the present invention on a skid 100
is preferable for well site operations because skid 100 containing
the present invention may be loaded onto a truck and moved from one
location to another.
[0040] FIG. 3 depicts the surface equipment that is needed to drill
an under balanced well using the present invention. Some of the
equipment shown such as drilling derrick 400, drilling fluid pump
402, and mud tank/solids control equipment 406 are used in most
conventional drilling operations. Other equipment for under
balanced drilling, such as four-phase (oil, water, cuttings, and
gas) separator 404, flare stack 405, oil storage tanks 409, and
drilling fluid storage tanks 408, are also shown. Skid 100 is
located sufficiently close to the other surface equipment so that
the nitrogen from the present invention can be used in under
balanced drilling.
[0041] FIG. 4 is an illustration of the process of secondary
reservoir recovery using the present invention. Skid 100 produces
nitrogen that is injected into the reservoir through a gas
injection well. The gas permeates through the viscible regions of
the formation and pushes the oil towards the producing wells. The
oil may then be pumped to the surface using the production wells.
Persons of ordinary skill in the art are aware of how to configure
a plurality of wells for secondary recovery when a source of
nitrogen gas, such as skid 100, is present.
[0042] FIG. 5 is an illustration of the pipeline cleaning apparatus
using the present invention. Skid 100 produces nitrogen that is
injected into the pipeline behind a cleaning device called the pig.
The nitrogen gas forces the pig through the pipeline where the pig
cleans the inside of the pipeline. The pig is captured at a
receiver station. Persons of ordinary skill in the art are aware of
how to clean a pipeline with a pig when a source of nitrogen gas,
such as skid 100, is present.
[0043] With respect to the above description, it is to be realized
that the optimum dimensional relationships for the parts of the
invention, to include variations in size, materials, shape, form,
function, manner of operation, assembly, and use are deemed readily
apparent and obvious to one of ordinary skill in the art. The
present invention encompasses all equivalent relationships to those
illustrated in the drawings and described in the specification. The
novel spirit of the present invention is still embodied by
reordering or deleting some of the steps contained in this
disclosure. The spirit of the invention is not meant to be limited
in any way except by proper construction of the following
claims.
* * * * *